ACIP recommendations on dengue vaccination still pending
The Advisory Committee on Immunization Practices, or ACIP, could make recommendations on the use of a newly approved dengue vaccine in U.S. children as early as October, the chair of the ACIP’s dengue vaccines work group said.
The work group provided an update on its discussions during last month’s ACIP meeting. The FDA approved Dengvaxia (CYD-TDV, Sanofi Pasteur) last May for use in children aged 9 to 16 years living in endemic areas of the U.S., including Puerto Rico, which the ACIP work group noted is expected to experience a “substantial” dengue outbreak this year.
“Hopefully we'll be able to talk about it [at the ACIP meeting in June], and then at the October meeting have enough information together to say what we think ought to be done,” work group chair Robert Atmar, MD, a professor of infectious diseases at the Baylor College of Medicine, told Healio.
The vaccine, which protects against disease caused by all four dengue serotypes, is approved only for children with laboratory confirmation of a previous dengue infection because it can act as an initial dengue infection, putting the recipient at risk for more serious disease if they have not been infected at least once previously and are infected again.
“It's that second infection that has been associated with an increased risk of more severe disease,” Atmar said.
‘Quite a challenge’
Dengue has been endemic in Puerto Rico for almost 50 years, the work group noted. It infects roughly 60% of the population by the second decade of life, and 80% by the third.
In order to receive the vaccine, an individual must test positive for dengue antibodies. Currently, there are only two diagnostic tests that are commercially available to test for the presence of dengue antibodies, but neither has been approved by the FDA, Atmar said.
“They’re both being used under a mechanism whereby the lab validates its consistency, and to a certain degree, its sensitivity and specificity in their own laboratory,” Atmar said.
In Puerto Rico, tests must be conducted by a certified lab technician inside of a commercial laboratory. However, there are only two such locations in the territory, Ines O. Esquilin, MD, a pediatric ID specialist in San Juan, Puerto Rico, said during the ACIP meeting.
“As I understand it, diagnostic testing is not allowed in the physician's office by Puerto Rican law. They actually have to go to a commercial laboratory to get the testing done,” Atmar said. “Then that result has to be reported back to the clinician, who then decides whether or not it's appropriate for the child to get vaccinated. Then they have to go to a vaccine center to get vaccinated, at least for the majority of the pediatric population. And so, from a logistics standpoint, that's quite a challenge.”
The vaccine is administered in three separate doses, at 0, 6 and 12 months.
Hurricane Maria, which hit Puerto Rico in September 2017, knocked out electricity to all hospitals other than the territory’s main hospital in San Juan, Esquilin said. As a result, all patient documents are on paper, she added. Electronic vaccination records are working and available, however, so providers can see if and when a patient was given any of the three vaccine doses and can prepare patients for an upcoming dose.
But because there is no documentation for patients, health care providers do not know whether patients have been previously infected, just if they have been administered any form of the vaccine. Hence the need for diagnostic tests.
“One of the main things that we've been concerned about, both at the ACIP and in the work group, is the performance of the assays that are currently available — and that's not to say that they’re not adequate, it's just we don't know that because they haven't gone through the FDA approval process,” Atmar said.
One issue is the risk for a false positive for prior dengue infection, which would place a vaccinated but not previously infected child at higher risk for serious disease, Atmar said. He said other companies are developing tests.
“There are a lot of steps involved in the use of this vaccine, something that has not been the case previously with any vaccine that we've worked with,” said Infectious Diseases in Children Editorial Board Member and ACIP chair José R. Romero, MD, the section chief of pediatric infectious diseases at Arkansas Children’s Hospital and the University of Arkansas for Medical Sciences.
Another challenge that Puerto Ricans may face is paying for the vaccine once they are cleared to receive it. Insurance companies typically do not cover vaccines if they are not recommended by the ACIP, Atmar said.
“If it's recommended by the ACIP, the ACIP also ends up making a recommendation about whether it should be covered under the Vaccines for Children program. If it's covered there, then children who have challenges from an income standpoint can get it through the health department at no cost,” he said.
The diagnostic tests are not covered by the VFC program but may be covered by insurance.
“There's not currently a mechanism to cover the cost of the blood test, and that, depending upon who's doing it and where it's being done, may not be a trivial cost,” Atmar said. – by Ken Downey Jr.
Disclosures: Atmar and Romero report no financial disclosures.